SQLite: GROUP BY Clause

This SQLite post explains how to use the SQLite GROUP BY clause with syntax and examples.

Description

The SQLite GROUP BY clause is used in a SELECT statement to collect data across multiple records and group the results by one or more columns.

Syntax

The syntax for the GROUP BY clause in SQLite is:

SELECT expression1, expression2, ... expression_n, 
       aggregate_function (expression)
FROM tables
[WHERE conditions]
GROUP BY expression1, expression2, ... expression_n;

Parameters or Arguments

expression1, expression2, ... expression_n

The expressions that are not encapsulated within an aggregate function and must be included in the GROUP BY clause.

aggregate_function

A function such as sum, count, min, max, or avg functions.

tables

The tables that you wish to retrieve records from. There must be at least one table listed in the FROM clause.

WHERE conditions

Optional. The conditions that must be met for the records to be selected.

Example - Using sum function

Let's look at an example that shows how to use the GROUP BY clause with the sum function in SQLite.

This SQLite GROUP BY example uses the sum function to return the last_name and the total salaries (for the last_name).

SELECT last_name, sum(salary) AS "Total salaries"
FROM employees
GROUP BY last_name;

Because you have listed one column (the last_name field) in your SELECT statement that is not encapsulated in the sum function, you must use the GROUP BY clause. The last_name field must, therefore, be listed in the GROUP BY clause.

Example - Using count function

Let's look at an example that shows how to use the GROUP BY clause with the count function in SQLite.

This GROUP BY example uses the count function to return the favorite_website and the number of employees (for that favorite_website) that have an employee_id less than 50.

SELECT favorite_website, count(*) AS "Number of employees"
FROM employees
WHERE employee_id  50
GROUP BY favorite_website;

Example - Using MIN function

Let's next look at how we could use the GROUP BY clause with the min function in SQLite.

This GROUP BY example uses the min function to return the name of each department and the minimum salary in the department.

SELECT department, min(salary) AS "Lowest salary"
FROM employees
GROUP BY department;

Example - Using max function

Finally, let's look at how we could use the GROUP BY clause with the max function in SQLite.

This GROUP BY example uses the max function to return the name of each department and the maximum salary in the department.

SELECT department, max(salary) AS "Highest salary"
FROM employees
GROUP BY department;